Fugitive tinting of synthetic fibers



United States Patent Int. Cl. D06p 1/00 US. Cl. 8-164 6 Claims ABSTRACT OF THE DISCLOSURE Fugitive tinting of articles made of synthetic fibers is accomplished by contacting the fibers with a hydrolyzed anthocyan dye.

This invention relates to the dyeing of synthetic fibers. In a more particular sense, the invention relates to the fugitive tinting of synthetic fibers by using natural coloring matters.

Fugitive tints, commonly known as sighting colors, are useful for the purpose of identifying fibers, yarns, threads and the like during the processes of carding, roving, spinning, weaving, etc. The tints should be capable of readily coloring the fibers and, after the processing of the fibers, should be capable of being readily removed by rinsing the fibers with water and/or a simple scouring operation.

The problem in tinting most synthetic fibers is that the tints can not be readily removed by a Simple scouring procedure and leave the fibers stained. Where the fibers are strained, a more complica ted and expensive scouring procedure is usually necessary to clean the fibers. In some cases the fibers are permanently stained and must be discarded. This problem is compounded during the processing of tinted fibers where they are sometimes treated with steam, e.g. high twist yarns are steam treated to reduce the kinkiness thereof and make them more workable for processing. The steam treatment often sets an otherwise fugitive tint on the fiber and renders it more difficult or almost impossible to remove the tint by a simple scour.

High-twist nylon yarn is an example of a synthetic fiber where the selection of fugitive tints is important. The high-twist yarn is usually subjected to steam treatment to reduce the kinkiness of the yarn. This treatment "softens the fiber and permits the ingress of the tint into the fiber. With some tints, the steam treatment decomposes the tint and the decomposed products stain the fiber. A simple scouring procedure is usually ineffective to remove the tint from the yarn and a more complicated and expensive scour is necessary. In some cases the nylon. is permanently stained.

It is therefore an object of this invention to provide a method for fugitive tinting synthetic fibers, yarns, fabrics, etc.

Another object of this invention is to provide a method for fugitive tinting articles made of synthetic fibers wherein the tint can be readily removed by a water rinse and/ or a simple scour.

These and other objects of this invention are accomplished by providing a method of fugitive tinting articles made of synthetic fibers comprising contacting the fiber with a hydrolyzed anthocyan dye. Natural fibers are not useful with the invention because the anthocyan dye cannot be removed from these fibers by a simple scour.

The synthetic fibers useful in the invention include ac tate fibers, acrylic fibers, modacrylic fibers. polyamide fibers, polyester fibers, and rayon fibers. Acetate fibers can be defined as fibers in which the fiber-forming substance is cellulose acetate and wherein no less than 92% of the hydroxyl groups are acetylated, the term triacetate may be used as a generic description of the fiber. Acrylic fibers are defined as fibers in which the fiber-forming substance is any long-chain synthetic polymer composed of at least by weight of acrylonitrile units. Modacrylic fibers are defined as fibers in which the fiber-forming substance is any long-chain synthetic polymer composed of less than 85% but at least 35% by weight of acrylonitrile units. Polyamide fibers, which are particular useful with this invention, include fibers in which the fiberforming substance is any long-chain synthetic polyamide having recurring amide groups (CONH) as an integral part of the polymer chain. Polyester fibers, which are also particularly useful with the invention, include fibers in which the fiber-forming substance is any longchain synthetic polymer composed of at least 85% by weight of an ester of a dihydric alcohol and a dibasic acid such as terephthalic acid. Also useful with the invention are rayon fibers which can be defined as fibers composed of regenerated cellulose as well as manufactured fibers composed of regenerated cellulose in which substituents have replaced not more than 5% of the hydrogens of the hydroxyl groups.

The. fugitive tints useful with the invention include those dyestuffs belonging to the anthocyan group. Anthocyans as used herein are defined as coloring matters which are responsible for the red, violet, and the blue pigmentations of flowers, of many fruits and vegetables and to some extent of other plant tissues. These anthocyans are derivatives of Z-phenylbenzopyrilium salts and most of them, with the exception of a few amino-derivatives, are hydroxyl-derivatives existing usually in the plant as glycosides. Nitrogenous anthocyans occurring in red beets is a particularly useful anthocyan dye. It is preferred that the anthocyans be converted to the sugar-free pigments. This can be accomplished by hydrolysis, e.g. by boiling the anthocyan dyestuffs for a short time in a mildly acidic solution, for example in an aqueous solution containing about 0.1% citric acid.

The anthocyan dyes or fugitive tints useful in the invention can be obtained by boiling anthocyan dye producing fruits, vegetables, or flowers in a solution containing a mild acid, such as citric, acetic, lactic, oxalic, etc. Thereafter, the anthocyan extract can be separated from the mixture of conventional means such as filtration, centrifugation, etc. The anthocyan extract can then be applied as a tint to the fiber or article made of the fiber by spraying, dipping, kiss rolling, padding, etc. Exam les of useful fruits, vegetables, and flowers, include beets, leaves of sorrel plants, poppy plants, beech acorn, red rose, purple and black pansy plants, hazel plants, etc. An example of a particularly useful anthocyan dye is aqueous beet extract prepared by boiling, for a period of time ranging from about 10 to about 60 minutes, red beets separated from its leaves in an aqueous solution containing from about .01 to about 25 percent of citric acid. The beet mixture is then separated from the solids by filtration to produce an aqueous beet extract useful as a fugitive tint.

As mentioned previously, the fugitive tints can be extracted in an aqueous medium containing a mild acid. Mediums other than water such as ethyl acetate and benzene are also useful as extract solvents. From an economical standpoint, however, an aqueous medium is preferred.

The amount of anthocyan tint useful to color the synthetic fibers or articles made from the fibers is not critical as long as the amount is sufiicient to color the fiber. Amounts within the range of from about .005 ot about 5% of the anthocyan dye, based on the weight of the fiber, are useful examples within the invention. From an economical basis, amounts sufiicient to slightly tint the fiber, for example amounts ranging from about 0.1% to about 2%, based on the weight of fiber, are useful to 3 tint or color the fiber. If a deeper color is desired, amounts ranging up to about or more are useful. Concentrations of the same tint can be varied to give light, medium, and deeper shades of the tint to the same or different synthetic fibers.

The tints can be applied to the fibers by spraying, dipping, kiss rolling, padding, etc. at temperatures ranging from about 65 F. to about the boiling point or decomposition temperature of the anthocyan dye, whichever is lower. Temperatures at about room temperature are preferred from a convenience basis. After the tint is applied, the article can be dried at temperatures within the range of from about 200 F. up to the lower decomposition temperature of either the anthocyan dye or the fiber. Also, tinted articles made from the fibers can be steam treated without any adverse effect on the subsequent removal of the tint from the article.

The tint can be removed from the fiber by a water rinse and/or a simple scour. Water rinsing can remove up to about 95% of the tint. A simple scour, for example an aqueous solution containing from about 0.5 to about 2 grams per liter of a conventional surface active chemical, at about 140 F., can remove all the tint and leave the fiber unstained. The tint can even be removed where the fiber or articles made from the fibers are subjected to a steam treatment during the processing thereof, an example of this treatment is where yarn is steam treated at 205-210 F. before a Weaving operation.

The following examples are presented to afford a more detailed description of the invention. It is to be understood that the following examples are not to be read as a limitation of the invention but are presented as specific working examples of the invention. Where percents are used they are based on weight, unless otherwise specified.

EXAMPLE I An aqueous extract from red beets is prepared by boiling 1 kilogram of beets for one hour in 1 liter of water containing about 0.05% citric acid. The mixture is filtered and a filtrate having a deep blue, red color is obtained. A sample of nylon textile yarn is tinted with the filtrate by padding at room temperature and then drying at 200 F. Thereafter, the tinted yarn is treated with steam at 205 210 F. for about 2 minutes. The tinted yarn is rinsed in distilled water at 120 F. for 5 minutes, and is then scoured for 5 minutes at 140 F. in an aqueous solution containing 2 grams per liter of soda ash and 2 grams per liter of an anionic surfactant. The water rinse removed about 95% of the tint and the scour removed completely all traces of the tint.

EXAMPLE II The procedure of Example I is repeated using acetate, acrylic, and polyester textile yarn samples. With each sample, the water rinse removed about 95% of the tint from the fiber and the scour removed completely all traces of the tint.

EXAMPLE III An aqueous extract from leaves of a sorrel plant is prepared by boiling 2 kilograms of sorrel leaves in 1.5 liters of water and then filtering the mixture. A filtrate having a dark green shade is obtained. A sample of polyester textile yarn is padded at room temperature with the filtrate and then dried at 200 F. Thereafter the tinted sample is steam treated at 205 -210 F. for about 2 minutes and dried again at 200 F. The tinted yarn is then rinsed for 5 minutes at 120 F. in distilled water. The rinse removed about 95% of the tint from the fiber. Thereafter, the yarn is scoured for 5 minutes at 140 F. in an aqueous solution containing 2 grams per liter of soda ash and 2 grams per liter of an anionic surfactant. The scour comp y m ed a l t a e 9 t e i from h y 4 EXAMPLE 1v Samples of acetate, acrylic, and polyamide fibers are treated as described in Example III. With each fiber sample, about of the tint is removed by the water rinse and all traces of tint are completely removed by the scour.

EXAMPLE V A multi-fiber strip containing fiber samples of acetate, acrylic, modacrylic, polyamide, polyester, rayon, silk and wool is padded at room temperature with an aqueous extract of red beets. The strip is then dried at 200 F. and is steam treated for 1.5 minutes at 210 F. Upon examining the multi-fiber strip, the acetate, acrylic, polyamide, polyester, and silk fibers showed a light shade of pink, the modacrylic fiber showed a medium shade of brown, the rayon fiber showed a heavy shade of pink, and the wool fiber showed a medium shade of pink. The tinted fiber strip is then rinsed in tap Water at room temperature for 15 minutes. Upon examining the fiber strip, it showed that in all fiber samples except silk and wool about 95% of the tint is removed. The fiber strip is then scoured at F. for 15 minutes in an aqueous solution containing 2 grams per liter of soda ash and 2 grams per liter of a non-ionic surface active agent (Sterox NL, Monsanto Chemical Co.). The scour removed completely all traces of tint in the fiber samples except silk and wool, the latter two fiber samples being stained.

What is claimed is:

1. A method of fugitive tinting articles made of synthetic fibers comprising contacting the fibers at temperatures of from about 65 F. up to about the boiling point of the dye with an amount of from about 0.005% up to about 5% based on the weight of the fiber of a hydrolyzed anthocyan dye, whereby the tint can be subsequently removed from the article by means of a scouring at about 140 F. with an aqueous solution containing from about 0.5 to about 2 grams per liter of a conventional surface active chemical, even after steam treatment of the tinted article.

2. The method of claim 1 wherein the fiber is polyamide fiber.

3. The method of claim 1 wherein the fiber is polyester fiber.

4. The method of claim 1 wherein the fiber is acrylic fiber.

5. The method of claim 1 wherein the hydrolyzed anthocyan dye is an aqueous extract of red beets.

6. The method of claim 1 wherein the coloring matter is an aqueous extract of leaves from a sorrel plant.

References Cited UNITED STATES PATENTS 1,273,293 7/1918 Warkup 853 FOREIGN PATENTS 6,270 1832 Great Britain. 2,563 6 Great Britain.

OTHER REFERENCES M. G. Morrow: Science News Letter, Aug. 23, 1947, pp. 122 and 123.

C. L. Bird et al.: J.S.D.C. 66, August 1950, pp. 423 through 434.

A. O. Fligor: The Spotting Manual of the Drycleaning Industry, rev. ed., June 1946, pp. 105 and 106.

GEORGE F. LESMES, Primary Examiner T. .T. HERBERT, JR., Assistant Examiner 

